Devices and methods related to high power diode switches with low DC power consumption

ABSTRACT

Devices and methods are disclosed, related to high power diode switches. In some embodiments, a radio-frequency switch circuit can include a first switchable path implemented between a pole and a first throw, the first switchable path including one or more PIN diodes, and a second switchable path implemented between the pole and a second throw, the second switchable path including one or more PIN diodes. The radio-frequency switch circuit can further include a switchable shunt path implemented between the second throw and a ground, the switchable shunt path including at least one shunt PIN diode and a capacitance between the second throw and the at least one shunt PIN diode. The pole can be an antenna port, and the first and second throws can be transmit and receive ports, respectively.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Application No.62/186,852 filed Jun. 30, 2015, entitled DEVICES AND METHODS RELATED TOHIGH POWER DIODE SWITCHES WITH LOW DC POWER CONSUMPTION, the disclosureof which is hereby expressly incorporated by reference herein in itsentirety.

BACKGROUND

Field

The present disclosure relates to diode switches for radio-frequency(RF) applications.

Description of the Related Art

In some radio-frequency (RF) applications, signals can be routed betweenan antenna and a transceiver through, for example, one or more transmitpaths and one or more receive paths. Such routing of signals can befacilitated by switches.

SUMMARY

In accordance with some implementations, the present disclosure relatesto a radio-frequency (RF) switch circuit that includes a firstswitchable path implemented between a pole and a first throw, the firstswitchable path including one or more PIN diodes, a second switchablepath implemented between the pole and a second throw, the secondswitchable path including one or more PIN diodes, and a switchable shuntpath implemented between the second throw and a ground, the switchableshunt path including at least one shunt PIN diode and a capacitancebetween the second throw and the at least one shunt PIN diode.

In some embodiments, the pole is an antenna port. In some embodiments,the first throw is a transmit port configured to receive an amplifiedradio-frequency signal. In some embodiments, the radio-frequency switchcircuit further comprises an additional switchable shunt pathimplemented between the transmit port and a ground.

In some embodiments, the additional switchable shunt path includes atleast one shunt PIN diode. In some embodiments, the radio-frequencyswitch circuit further comprises a transmit bias port electricallyconnected to a node between the first throw and the one or more PINdiodes of the first switchable path.

In some embodiments, the second throw is a receive port configured tooutput a received signal. In some embodiments, the radio-frequencyswitch circuit further comprises a receive bias port electricallyconnected to a node between the second throw and the one or more PINdiodes of the second switchable path. In some embodiments, theradio-frequency switch circuit further comprises a receive shunt biasport electrically connected to a node between the capacitance and the atleast one shunt PIN diode of the switchable shunt path.

A method is disclosed, for operating a radio-frequency switch circuit ina transmit mode. In some embodiments, the method comprises activating afirst switchable path including one or more PIN diodes implementedbetween an antenna port and a transmit port, by applying a forward biasto the one or more PIN diodes of the first switchable path. The methodfurther comprises deactivating a second switchable path including one ormore PIN diodes implemented between the antenna port and a receive port,by applying a reverse bias to the one or more PIN diodes of the secondswitchable path, and activating a switchable shunt path implementedbetween the receive port and a ground, and including at least one shuntPIN diode and a capacitance between the receive port and the at leastone shunt PIN diode, by applying a forward bias to the at least oneshunt PIN diode of the switchable shunt path.

In some embodiments, applying the forward bias to the one or more PINdiodes includes applying a forward bias voltage to a transmit bias portelectrically connected to a node between the transmit port and the oneor more PIN diodes of the first switchable path. In some embodiments,applying the reverse bias to the one or more PIN diodes includesapplying a reverse bias voltage to a receive bias port electricallyconnected to a node between the receive port and the one or more PINdiodes of the second switchable path.

In some embodiments, applying a forward bias to the at least one shuntPIN diode includes applying a forward bias voltage to a receive shuntbias port electrically connected to a node between the capacitance andthe at least one shunt PIN diode of the switchable shunt path.

According to some teachings, the present disclosure relates to anantenna switch module (ASM) that includes a grounding pad and anelectrical insulator layer implemented over the grounding pad. The ASMfurther includes a switch circuit having a first switchable pathimplemented between an antenna port and a transmit port, the firstswitchable path including one or more PIN diodes implemented over theelectrical insulator layer. The switch circuit further includes a secondswitchable path implemented between the antenna port and a receive port,the second switchable path including one or more PIN diodes implementedover the electrical insulator layer. The switch circuit further includesa switchable shunt path implemented between the receive port and aground, the switchable shunt path including at least one shunt PIN diodeimplemented over the electrical insulator layer and a capacitancebetween the receive port and the at least one shunt PIN diodeimplemented over the electrical insulator layer.

In some embodiments, the electrical insulator layer is a thermalconductor thereby allowing conduction of heat between a PIN diode andthe grounding pad. In some embodiments, the electrical insulator layerincludes aluminum nitride (AIN).

In some embodiments, each PIN diode is secured to the electricalinsulator layer by a thermally conductive adhesive. In some embodiments,the electrical insulator layer is secured to the grounding pad by athermally conductive adhesive. In some embodiments, the antenna switchmodule further includes an overmold implemented over the electricalinsulator layer, with the overmold being dimensioned to encapsulate atleast the PIN diodes of the switch circuit.

In some implementations, the present disclosure relates to a method forfabricating a radio-frequency (RF) module. The method includes providingor forming an electrical insulator layer. The method further includesforming a switch circuit including a first switchable path implementedbetween a pole and a first throw, the first switchable path includingone or more PIN diodes implemented over the electrical insulator layer.The method further includes forming the switch circuit to furtherinclude a second switchable path implemented between the pole and asecond throw, the second switchable path including one or more PINdiodes implemented over the electrical insulator layer, the switchcircuit further including a first switchable shunt path implementedbetween the second throw and a ground, the switchable shunt pathincluding at least one shunt PIN diode implemented over the electricalinsulator layer and a capacitance between the second throw and the atleast one shunt PIN diode implemented over the electrical insulatorlayer. The method further includes forming a grounding pad under theelectrical insulator layer such that the grounding pad is electricallyinsulated from each of the PIN diodes of the switch circuit.

In a number of implementations, the present disclosure relates to aradio-frequency system that includes an antenna, a transceiver incommunication with the antenna, and a transmit/receive switchimplemented between the antenna and the transceiver. Thetransmit/receive switch includes a grounding pad and an electricalinsulator layer implemented over the grounding pad. The transmit/receiveswitch further includes a switch circuit having a first switchable pathimplemented between an antenna port and a transmit port, the firstswitchable path including one or more PIN diodes implemented over theelectrical insulator layer. The switch circuit further includes a secondswitchable path implemented between the antenna port and a receive port,the second switchable path including one or more PIN diodes implementedover the electrical insulator layer. The switch circuit further includesa switchable shunt path implemented between the receive port and aground, the switchable shunt path including at least one shunt PIN diodeimplemented over the electrical insulator layer and a capacitancebetween the receive port and the at least one shunt PIN diodeimplemented over the electrical insulator layer.

In some embodiments, the radio-frequency system is implemented as a basestation. In some embodiments, the first switchable path is configured tohandle high power associated with amplified transmit signals associatedwith the base station.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the inventions have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment of the invention.Thus, the invention may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other advantages as may be taughtor suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example topology of a radio-frequency (RF) switchcircuit having one or more input ports and one or more output ports.

FIG. 2 shows an example RF switch circuit that includes a plurality ofPIN diodes that can be configured to provide the functionality of theswitch of FIG. 1.

FIG. 3 shows an example topology of an RF switch circuit having a commonport and a plurality of RF ports.

FIG. 4 shows an example RF switch circuit that includes a plurality ofPIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 3.

FIG. 5 shows an example topology of an RF switch circuit having a commonantenna port ANT, a transmit port TX, and a receive port RX.

FIG. 6 shows an example RF switch circuit that includes a plurality ofPIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 5.

FIG. 7 shows another example RF switch circuit that includes a pluralityof PIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 5.

FIG. 8 shows another example RF switch circuit that includes a pluralityof PIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 5.

FIG. 9 shows an example module in which a plurality of PIN diodes can bemounted on their respective electrical insulator structures.

FIG. 10 shows an example module in which a plurality of PIN diodes canbe mounted on a common electrical insulator substrate.

FIG. 11 shows an example pin layout that can be implemented for theexamples of FIGS. 9 and 10 in an example QFN packaging format.

FIG. 12 shows an example configuration where a module is mounted on aprinted circuit board (PCB).

FIG. 13 shows that in some embodiments, a switching circuit or a switchmodule having one or more features as described herein can beimplemented in an RF system.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

PIN diodes are utilized in some radio-frequency (RF) applications, suchas applications involving high power RF signals. For example, a PINdiode can be utilized as a fast switch to provide switchingfunctionality in RF applications involving high power signals. Describedherein are various examples of devices and methods related to RFswitches that utilize PIN diodes. Although various examples aredescribed herein in the context of PIN diodes, it will be understoodthat one or more features of the present disclosure can also beimplemented in applications involving other types of diodes. Similarly,although various examples are described herein in the context of RFswitches, it will be understood that one or more features of the presentdisclosure can also be implemented in other types of applications,including non-switching RF applications.

In broad-bandwidth, high-power RF switching applications, PIN diodes canbe connected in a series or series/shunt configuration between one ormore input ports and one or more output ports. When implemented as such,it is desirable or required to have the cathode contact of a PIN diodebe electrically isolated from the ground, and at the same time, havevery low thermal impedance to ground to conduct heat out of the switch.

In switches having high RF isolation performance, shunt diodes may alsobe employed. For systems which only have positive control voltage orcurrent available, one terminal of a shunt diode typically needs to beAC-coupled to a system ground, and reduced or minimized thermalimpedance for such a coupling path is typically desirable.

For the purpose of description, PIN diodes, shunt diodes, or simplydiodes can be implemented as, for example, silicon-based devices. Othersemiconductor process technologies can also be utilized in the PINdiodes/shunt diodes/diodes as described herein.

Described herein various examples of switching devices having desirablefeatures such as low thermal impedance, high RF isolation, and/or lowinsertion loss. Various switching topologies can be implemented inpackaging configurations as described herein to benefit from one or moreof the foregoing features, and non-limiting examples of such switchingtopologies are described in reference to FIGS. 1-8.

FIG. 1 shows an example symmetrical topology of an RF switch circuit 100having one or more input ports (e.g., IN_1 or IN_2) and one or moreoutput ports (e.g., OUT_1 or OUT_2). A switch 102 can be electricallyconnected between the input port and the output port along an RF path.In an ON state (e.g., achieved by providing a forward bias), the switch102 is depicted as being closed, thereby completing the RF path betweenthe input port and the output port. In an OFF state (e.g., achieved byproviding a reverse bias), the switch 102 is depicted as being open,thereby breaking the RF path between the input port and the output port.

FIG. 2 shows an example RF switch circuit 100 that includes a pluralityof PIN diodes that can be configured to provide the functionality of theswitch 102 of FIG. 1. In the example of FIG. 2, there are two inputports (IN_1, IN_2) and two output ports (OUT_1, OUT_2); however, it willbe understood that other numbers of input port(s) and output port(s) canbe utilized.

In FIG. 2, a path between IN_1 and OUT_1 can be formed through a firstPIN diode 110, a node 112, and a second PIN diode 114. Similarly, a pathbetween IN_2 and OUT_2 can be formed through a third PIN diode 116, anode 118, and a fourth PIN diode 120. If a path between IN_1 and OUT_2is desired, such a path can be formed through the first PIN diode 110,the nodes 112, 118, and the fourth PIN diode 120. Similarly, if a pathbetween IN_2 and OUT_1 is desired, such a path can be formed through thethird PIN diode 116, the nodes 118, 112, and the second PIN diode 120.Table 1 lists states of the four PIN diodes that can be implemented toachieve the foregoing example paths. For the purpose of description ofFIG. 2 and Table 1, it will be assumed that a forward bias on a PINdiode corresponds to an ON state, and a reverse bias corresponds to anOFF state.

TABLE 1 Input Output PIN PIN port port PIN diode 110 diode 114 PIN diode116 diode 120 IN_1 OUT_1 ON ON OFF OFF IN_2 OUT_2 OFF OFF ON ON IN_1OUT_2 ON OFF OFF ON IN_2 OUT_1 OFF ON ON OFF

FIG. 3 shows an example topology of an RF switch circuit 130 having acommon port RFC and a plurality of RF ports (e.g., RF1 and RF2). Such atopology can be implemented as a single-pole-double-throw (SPDT) withsymmetrical switching paths (RF1 and RF2 as the two throws) from asingle common port (RFC as the single pole).

A signal path between RFC and RF1 can be achieved with a switch 134being closed (ON), a shunt switch 138 (between node 136 and ground)being open (OFF), a switch 140 being open (OFF), and a shunt switch 144(between node 142 and ground) being closed (ON). Similarly, a signalpath between RFC and RF2 can be achieved with the switch 140 beingclosed (ON), the shunt switch 144 (between node 142 and ground) beingopen (OFF), the switch 134 being open (OFF), and the shunt switch 138(between node 136 and ground) being closed (ON). In the example of FIG.3, the shunt path between node 136 and ground can provide improvedisolation for the port RF1 (with the switch 138 closed) when the pathbetween RFC and RF1 is open. Similarly, the shunt path between node 142and ground can provide improved isolation for the port RF2 (with theswitch 144 closed) when the path between RFC and RF2 is open.

FIG. 4 shows an example RF switch circuit 130 that includes a pluralityof PIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 3. In theexample of FIG. 4, a first bias port (RF1_BIAS) for the first shuntdiode switch can be provided. Similarly, a second bias port (RF2_BIAS)for the second shunt diode switch can be provided.

In FIG. 4, a first path between RFC and RF1 can be formed through afirst PIN diode 152 and node 154. A shunt path for the foregoing firstpath can be provided between node 154 and ground through a second PINdiode 156, node 158, and a capacitance 160. Similarly, a second pathbetween RFC and RF2 can be formed through a third PIN diode 162 and node164. A shunt path for the foregoing second path can be provided betweennode 164 and ground through a fourth PIN diode 166, node 168, and acapacitance 170. Table 2 lists states of the four PIN diodes that can beimplemented to achieve the foregoing example paths. For the purpose ofdescription of FIG. 4 and Table 2, it will be assumed that a forwardbias on a PIN diode corresponds to an ON state, and a reverse biascorresponds to an OFF state.

TABLE 2 PIN PIN PIN PIN Active path diode 152 diode 156 diode 162 diode166 Between RFC and RF1 ON OFF OFF ON Between RFC and RF2 OFF ON ON OFF

FIG. 5 shows an example asymmetrical topology of an RF switch circuit180 having a common antenna port ANT, a transmit port TX, and a receiveport RX. Such a topology can be implemented as asingle-pole-double-throw (SPDT) with transmit and receive switchingpaths (TX and RX as the two throws) from a single common antenna port(ANT as the single pole).

In a transmit state, a signal path between ANT and TX can be achievedwith a switch 184 being closed (ON), a switch 186 being open (OFF), anda shunt switch 190 (between node 188 and ground) being closed (ON). In areceive state, a signal path between ANT and RX can be achieved with theswitch 184 being open (OFF), the switch 186 being closed (ON), and theshunt switch 190 (between node 188 and ground) being open (OFF). In theexample of FIG. 5, the shunt path between node 188 and ground canprovide improved isolation for the receive port RX (with the switch 190closed) when the transmission path between TX and ANT is active.

FIG. 6 shows an example RF switch circuit 180 that includes a pluralityof PIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 5. In theexample of FIG. 6, a receive bias port (RX_BIAS) for the receive shuntdiode switch can be provided.

In FIG. 6, a transmit path between TX and ANT can be formed through afirst PIN diode 202 and node 200. A shunt path for the foregoingtransmit path may or may not exist. A receive path between ANT and RXcan be formed through node 200, a second PIN diode 204, and node 206. Ashunt path for the foregoing receive path can be provided between node206 and ground through a third PIN diode 208, node 210, and acapacitance 212. Table 3 lists states of the three PIN diodes that canbe implemented to achieve the foregoing example paths. For the purposeof description of FIG. 6 and Table 3, it will be assumed that a forwardbias on a PIN diode corresponds to an ON state, and a reverse biascorresponds to an OFF state.

TABLE 3 Active path PIN diode 202 PIN diode 204 PIN diode 208 Between TXand ANT ON OFF ON Between ANT and RX OFF ON OFF

FIG. 7 shows an example RF switch circuit 190 that includes a pluralityof PIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 5 in accordancewith some implementations. While pertinent features are shown, those ofordinary skill in the art will appreciate from the present disclosurethat various other features have not been illustrated for the sake ofbrevity and so as not to obscure more pertinent aspects of the exampleimplementations disclosed herein. To that end, in the example of FIG. 7,a receive bias port (RX_BIAS) for the receive diode switch, a receiveshunt bias port (RX_SHT_BIAS) for the receive shunt diode switch, and atransmit bias port (TX_BIAS) for the transmit diode switch can beprovided.

In FIG. 7, a transmit path between TX and ANT can be formed through node224, a first PIN diode 202, and node 200. A shunt path for the foregoingtransmit path may or may not exist. A receive path between ANT and RXcan be formed through node 200, a second PIN diode 204, node 206, andnode 224. A shunt path for the foregoing receive path can be providedbetween node 206 and ground through a third PIN diode 208, node 210, anda capacitance 212. Table 4 lists states of the three PIN diodes that canbe implemented to achieve the foregoing example paths. For the purposeof description of FIG. 7 and Table 4, it will be assumed that a forwardbias on a PIN diode corresponds to an ON state, and a reverse biascorresponds to an OFF state.

TABLE 4 Active path PIN diode 202 PIN diode 204 PIN diode 208 Between TXand ANT ON OFF ON Between ANT and RX OFF ON OFF

According to some embodiments, when RF switch circuit 190 is in ANT-TXmode (e.g., when the transmit path between TX and ANT is active), areverse bias (e.g., >28 V) from the RX_BIAS port is applied to secondPIN diode 204 in order to restrict second PIN diode 204 fromself-rectification due to the high RF power levels present at the ANTport. According to some embodiments, when RF switch circuit 190 is inANT-TX mode, the same voltage that provides the reverse bias to secondPIN diode 204 is also the forward bias for third PIN diode 208 such thatRF energy passes through third PIN diode 208 to the ground in order toisolate the RX port. In some embodiments, the majority of this voltageis dropped across resistance 232. For example, the typical forwardcurrent level through resistance 232 is 30 mA. As such, in this example,resistance 232 handles approximately 810 mW of DC power.

FIG. 8 shows an example RF switch circuit 195 that includes a pluralityof PIN diodes that can be configured to provide the functionality of theswitches associated with the switching topology of FIG. 5 in accordancewith some implementations. While pertinent features are shown, those ofordinary skill in the art will appreciate from the present disclosurethat various other features have not been illustrated for the sake ofbrevity and so as not to obscure more pertinent aspects of the exampleimplementations disclosed herein. To that end, in the example of FIG. 8,a receive bias port (RX_BIAS) for the receive diode switch, a receiveshunt bias port (RX_SHT_BIAS) for the receive shunt diode switch, and atransmit bias port (TX_BIAS) for the transmit diode switch can beprovided.

In FIG. 8, a transmit path between TX and ANT can be formed through node224, a first PIN diode 202, and node 200. A shunt path for the foregoingtransmit path may or may not exist. A receive path between ANT and RXcan be formed through node 200, a second PIN diode 204, node 206, andnode 224. A shunt path for the foregoing receive path can be providedbetween node 206 and ground through capacitance 212, node 210, and athird PIN diode 208. Table 5 lists states of the three PIN diodes thatcan be implemented to achieve the foregoing example paths. For thepurpose of description of FIG. 8 and Table 5, it will be assumed that aforward bias on a PIN diode corresponds to an ON state, and a reversebias corresponds to an OFF state.

TABLE 5 Active path PIN diode 202 PIN diode 204 PIN diode 208 Between TXand ANT ON OFF ON Between ANT and RX OFF ON OFF

According to some embodiments, when RF switch circuit 195 is in ANT-TXmode (e.g., when the transmit path between TX and ANT is active), areverse bias (e.g., >28 V) from the RX_BIAS port is applied to secondPIN diode 204 in order to restrict second PIN diode 204 fromself-rectification due to the high RF power levels present at the ANTport. According to some embodiments, when RF switch circuit 195 is inANT-TX mode, capacitance 212 allows RF energy to pass through third PINdiode 208 to the ground in order to isolate the RX port. Moreover,capacitance 212 also blocks the reverse bias voltage from the RX_BIASport. As such, when RF switch circuit 195 is in ANT-TX mode, a separatelower forward bias voltage (e.g., 5 V) is applied to third PIN diode 208from the RX_SHT_BIAS port.

For example, when RF switch circuit 195 is in ANT-TX mode, the typicalforward current level through resistance 232 is 20 mA. As such, in thisexample, resistance 232 handles approximately 120 mW of DC power.

FIGS. 9 and 10 show examples of packaged modules 300 having PIN diodebased switching circuits as described herein. In some switchingapplications, it is desirable to have an electrode (e.g., cathode) of aPIN diode be electrically isolated from ground and at the same time beimplemented in a packaged module to allow effective removal of heat fromthe PIN diode. To address such design features, a PIN diode can bemounted on an electrical insulator having a low thermal impedance. Theelectrical insulator can be in physical contact (directly or through anintermediate layer) with a grounding pad, such that the PIN dioderemains electrically isolated from the grounding pad. If the electricalinsulator is thermally conductive, heat generated by the PIN diode canbe transferred to the grounding pad through the electrical insulator.

In the example module 300 of FIG. 9, a plurality of PIN diodes are shownto be mounted on their respective electrical insulator structures. Forexample, a first PIN diode 302 is mounted to a metal pattern 1000 on thetop of a first electrical insulator structure 314; and a second PINdiode 308 is mounted to a metal pattern 1001 on the top of a secondelectrical insulator structure 316. An electrode of the first PIN diode302 attached to metal pattern 1000 is shown to be electrically connectedto a first contact pad 306 through a wirebond 304, and an electrode ofthe second PIN diode 308 attached to metal pattern 1001 is electricallyconnected to a second contact pad 312 through a wirebond 310. The firstcontact pad 306 can be a TX port of, for example, the RF switch circuit195 of FIG. 8, and the second contact pad 312 can be an RX port of theRF switch circuit 195. In such a configuration, the first PIN diode 302can be, for example, PIN diode 202 in FIG. 8, and the second PIN diode308 can be PIN diode 204 of FIG. 8. Although not shown in FIG. 9, an ANTport and RX_SHT_BIAS port can be implemented as a contact pad of themodule 300. The ANT port electrical connection to the top of the PINdiodes 302 and 308 is also not shown.

In the example of FIG. 9, both of the electrical insulator structures314, 316 are shown to be coupled to a grounding pad 318. To facilitatethermal conduction between the PIN diodes 302, 308 and the grounding pad318, the PIN diodes 302, 308 can be adhered to metal patterns 1000 and1001 of their respective electrical insulator structures 314, 316 by,for example, thermally conductive epoxy. Such a thermally conductiveepoxy may or may not be electrically conductive. Further, the electricalinsulator structures 314, 316 can be adhered to the grounding pad 318by, for example, thermally conductive epoxy. Such a thermally conductiveepoxy may or may not be electrically conductive.

In the example of FIG. 9, an overmold 320 can be formed to encapsulatevarious components such as the PIN diodes 302, 308, the wirebonds 302,310, and the electrical insulator structures 314, 318. Such an overmoldcan be configured to yield a desirable package form factor that allowseasy handling and mounting onto a circuit board.

In the example module 300 of FIG. 10, a plurality of PIN diodes areshown to be mounted on a common electrical insulator substrate 315. Forexample, a first PIN diode 302 and a second PIN diode 308 are mounted onthe metal patterns 1000 and 1001 of electrical insulator substrate 315.An electrode of the first PIN diode 302 is shown to be electricallyconnected to a first contact pad 306 through a wirebond 304 and anelectrical path 322, and an electrode of the second PIN diode 308 iselectrically connected to a second contact pad 312 through a wirebond310 and an electrical path 324. The first contact pad 306 can be a TXport of, for example, the RF switch circuit 195 of FIG. 8, and thesecond contact pad 312 can be an RX port of the RF switch circuit 195.Although not shown in FIG. 10, an ANT port can be implemented as acontact pad of the module 300. In such a configuration, the first PINdiode 302 can be, for example, PIN diode 204 in FIG. 8, and the secondPIN diode 308 can be PIN diode 204 of FIG. 8.

In the example of FIG. 10, the electrical insulator substrate 315 isshown to be coupled to a grounding pad 318. To facilitate thermalconduction between the PIN diodes 302, 308 and the grounding pad 318,the PIN diodes 302, 308 can be adhered to the metal patterns 1000 and1001 of electrical insulator substrate 315 by, for example, thermallyconductive epoxy. Such a thermally conductive epoxy may or may not beelectrically conductive. Further, the electrical insulator substrate 315can be adhered to the grounding pad 318 by, for example, thermallyconductive epoxy. Such a thermally conductive epoxy may or may not beelectrically conductive. In some embodiments the grounding pad 318 thecontact pads 306, 312, and the metal patterns 1000 and 1001 can beformed on the surface of the electrical insulator substrate 315utilizing one or more metallization techniques.

In the example of FIG. 10, an overmold 320 can be formed over theelectrical insulator substrate 315 to encapsulate various componentssuch as the PIN diodes 302, 308 and the wirebonds 302, 310. Such anovermold can be configured to yield a desirable package form factor thatallows easy handling and mounting onto a circuit board.

In some embodiments, the electrical insulator structures 314, 316 andthe electrical insulator substrate 315 of FIGS. 9 and 10 can be formedfrom aluminum nitride (AIN). Such a material can provide desiredelectrical insulation property, as well as desired thermal conductanceproperty. It will be understood that other materials can also beutilized.

In some embodiments, the example modules 300 of FIGS. 9 and 10 can beimplemented in, for example, a quad-flat no-leads (QFN) package format.A significant portion of the heat generated by the PIN diodes under highpower RF signals can be conducted from the diode junctions to thegrounding pad through the AIN substrate(s). When such a module ismounted on a circuit board, the heat can be further transferred from thegrounding pad to a ground plane in the circuit board, and then toambient surrounding via a heat sink.

In the context of the example QFN packaging format, FIG. 11 shows anexample pin layout that can be implemented for the examples of FIGS. 9and 10. The grounding pad 318 can be implemented at or near the centerof the lower surface of the module 300. Various connection pins, such asthe TX pin 306 and the RX pin 312, can be implemented along theperiphery of the lower surface of the module 300.

FIG. 12 shows an example configuration 350 where a module 300 is mountedon a printed circuit board (PCB) 352. The module 300 can be either ofthe examples described in reference to FIGS. 9 and 10. The contact pads306, 312 (e.g., TX and RX ports) of the module 300 are shown to be incontact with their respective contact features 352, 354. The groundingpad 318 of the module 300 is shown to be in contact with a correspondinggrounding pad 356 on the PCB 352.

The grounding pad 356 is shown to be connected to a ground plane 360through a plurality of conductive vias 358 formed through a substratelayer 362 of the PCB 352. Thus, heat arriving at the contact pad 318 ofthe module 300 can be transferred through the contact pad 356 of the PCB352, through the vias 358, and to the ground plane 360.

In the example of FIG. 12, the ground plane 360 can be mounted to achassis 366 through, for example, a solder mask layer 364. Accordingly,heat arriving at the ground plane 360 can be dissipated into the chassis366.

FIG. 13 shows that in some embodiments, a switching circuit or a switchmodule having one or more features as described herein can beimplemented in an RF system 400. In the example RF system 400, atransmit/receive (T/R) switch 404 can include one or more PIN diodesimplemented as described herein. Such a T/R switch can allow use of acommon antenna 402 for transmit and receive operations. Such transmitand receive operations can be facilitated by switching actions of theT/R switch 404.

As shown in FIG. 13, the RF system 400 can include a transmit circuitconfigured to generate, amplify, filter, and transmit an RF signal. Suchan RF signal can be generated from a baseband subsystem (not shown) andan upconverter 414. The RF signal can then be filtered (e.g., by aband-pass filter 412) before being amplified by a power amplifier (PA)410. The amplified RF signal can further be filtered (e.g., by aband-pass filter 408) and be provided to the T/R switch 404 through path406 so as to be routed to the antenna 402.

As further shown in FIG. 13, a received signal from the antenna 402 canbe routed to a receiver circuit by the T/R switch 404 to a low-noiseamplifier (LNA) 424 (e.g., through path 420 and a band-pass filter 422).The output of the LNA 424 can be filtered further by a filter 426 (e.g.,a band-pass filter), and the filtered signal can be converted to anintermediate frequency (IF) signal for further processing. Such aconversion can be facilitate by a mixer 428, a local oscillator (LO)432, and a filter 430.

In some embodiments, the example RF system 400 can be implemented in abase station. In such an application, the amplified RF signal to betransmitted can have relatively high power, and the T/R switch 404 needsto be able to handle such power while maintaining desirable performancelevels. One or more features as described herein can be implemented insuch a T/R switch 404 to allow handling of high power while providingexcellent RF performance.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Description using the singularor plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A radio-frequency switch circuit comprising: afirst switchable path implemented between an antenna port and a firstthrow, the first switchable path including one or more PIN diodes; asecond switchable path implemented between the antenna port and a secondthrow, the second switchable path including one or more PIN diodes; anda switchable shunt path implemented between the second throw and aground, the switchable shunt path including at least one forward-biasedshunt PIN diode and a capacitance, and a shunt bias port connected to anode between the capacitance and the at least one forward-biased shuntPIN diode.
 2. The radio-frequency switch circuit of claim 1 wherein thefirst throw is a transmit port configured to receive an amplifiedradio-frequency signal.
 3. The radio-frequency switch circuit of claim 2further comprising an additional switchable shunt path implementedbetween the transmit port and a ground.
 4. The radio-frequency switchcircuit of claim 3 wherein the additional switchable shunt path includesat least one forward-biased shunt PIN diode.
 5. The radio-frequencyswitch circuit of claim 1 further comprising a transmit bias portelectrically connected to a node between the first throw and the one ormore PIN diodes of the first switchable path.
 6. The radio-frequencyswitch circuit of claim 1 wherein the second throw is a receive portconfigured to output a received signal.
 7. The radio-frequency switchcircuit of claim 1 further comprising a receive bias port electricallyconnected to a node between the second throw and the one or more PINdiodes of the second switchable path.
 8. An antenna switch modulecomprising: a grounding pad; an electrical insulator layer implementedover the grounding pad; and a switch circuit including a firstswitchable path implemented between an antenna port and a transmit port,the first switchable path including one or more PIN diodes implementedover the electrical insulator layer, the switch circuit furtherincluding a second switchable path implemented between the antenna portand a receive port, the second switchable path including one or more PINdiodes implemented over the electrical insulator layer, the switchcircuit further including a switchable shunt path implemented betweenthe receive port and a ground, the switchable shunt path including atleast one forward-biased shunt PIN diode implemented over the electricalinsulator layer and a capacitance, and a shunt bias port connected to anode between the capacitance and the at least one forward-biased shuntPIN diode implemented over the electrical insulator layer.
 9. Theantenna switch module of claim 8 wherein the electrical insulator layeris a thermal conductor thereby allowing conduction of heat between a PINdiode and the grounding pad.
 10. The antenna switch module of claim 9wherein the electrical insulator layer includes aluminum nitride (AIN).11. The antenna switch module of claim 8 wherein each PIN diode issecured to the electrical insulator layer by a thermally conductiveadhesive.
 12. The antenna switch module of claim 8 wherein theelectrical insulator layer is secured to the grounding pad by athermally conductive adhesive.
 13. The antenna switch module of claim 8further comprising an overmold implemented over the electrical insulatorlayer, the overmold dimensioned to encapsulate at least the PIN diodesof the switch circuit.
 14. The antenna switch module of claim 8 furthercomprising an additional switchable shunt path implemented between thetransmit port and the ground.
 15. A radio-frequency system comprising:an antenna; a transceiver in communication with the antenna; and atransmit/receive switch implemented between the antenna and thetransceiver, the transmit/receive switch including a grounding pad andan electrical insulator layer implemented over the grounding pad, thetransmit/receive switch further including a switch circuit having afirst switchable path implemented between an antenna port and a transmitport, the first switchable path including one or more PIN diodesimplemented over the electrical insulator layer, the switch circuitfurther including a second switchable path implemented between theantenna port and a receive port, the second switchable path includingone or more PIN diodes implemented over the electrical insulator layer,the switch circuit further including a switchable shunt path implementedbetween the receive port and a ground, the switchable shunt pathincluding at least one forward-biased shunt PIN diode implemented overthe electrical insulator layer and a capacitance, and a shunt bias portconnected to a node between the capacitance and the at least oneforward-biased shunt PIN diode implemented over the electrical insulatorlayer.
 16. The radio-frequency system of claim 15 wherein theradio-frequency system is implemented as a base station.
 17. Theradio-frequency system of claim 16 wherein the first switchable path isconfigured to handle high power associated with amplified transmitsignals associated with the base station.
 18. The radio-frequency systemof claim 16 wherein the second switchable path is associated withreceived signals associated with the base station.